BDNF Val66Met polymorphism moderates the association between sleep spindles and overnight visual recognition.

A common single nucleotide polymorphism (SNP) of the brain-derived neurotrophic factor (BDNF) gene, Val66Met, has been reported to impair BDNF secretion and memory function. However, few studies have investigated the interaction of BDNF genotype and sleep characteristics, such as sleep spindles, that promote long-term potentiation during sleep. In this study we compared overnight visual memory between the carriers of BDNF Met and non-carriers (Val homozygotes), and examined how sleep spindle density associated with memory performance. The sample constituted of 151 adolescents (mean age 16.9 years; 69% Val homozygotes, 31% Met carriers). The learning task contained high and low arousal pictures from Interactive Affective Picture System. The learning task and all-night polysomnography were conducted at the homes of the adolescents. Slow (10-13 Hz) and fast (13-16 Hz) spindles were detected with automated algorithm. Neither post-sleep recognition accuracy nor spindle density differed between Val homozygotes and Met carriers. While frontal slow and fast spindle densities associated with better recognition accuracy in the entire sample, examining the allelic groups separately indicated paralleling associations in Val homozygotes only. Interaction analyses revealed a significant genotype-moderated difference in the associations between frontal fast sleep spindles and high arousal pictures. In sum, sleep spindles promote or indicate visual learning in Val homozygote adolescents but not in Met carriers. The result suggests that the role of sleep spindles in visual recognition memory is not equal across individuals but moderated by a common gene variant.